Catalytic conversion apparatus



Feb; 9, 1943. F. M. McMlLLAN CATALYTIC CONVERSION APPARATUS Original Filed Jan. 27, 1941 lnvzni'or: Frank M. McMi bq his AHorncq:

Patented Feb. 9, 1943 CATALYTIC CONVERSION APPARATUS Frank M. McMillan, Berkeley, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Original application January 27, 1941, Serial No. 376,194. Divided and this application October 6, 1941, Serial No. 413,785

3 Claims.

The present invention relates to a process and apparatus for the more eflicient execution of reactions with solid catalysts. One preferred embodiment of the invention provides an improved process and apparatus for the execution of hydrocarbon conversions, such, in particular, as the vapor phase isomerization of butane, with supported catalysts. a

In effecting catalytic conversions with solid contact agents, either one of two methods is generally employed. In such cases, where the contact agent loses its activity relatively quickly and can be easily restored to its original activity (regenerative contact materials), it is the practice to employ the contact material in relatively short process or on-stream periods, during which the activity of the contact bed as a whole declines to a predetermined value, and to periodically restore the activity of the contact material between these process periods by a suitable treatment in situ. In other cases, where the contact material loses its activity more or less slowly over a considerable period of time and is not particularly amenable to a simple treatment in situ to restore the activity, it is the practice to replace the contact material when its activity has fallen to a predetermined level. Neither of these methods utilizes the contact material to the fullest possible advantage. Prolonging the conversion period of the process to such an extent that the greater part of the catalyst bed is exhausted shortens the useful life of the catalyst and entails continuance of operation during a considerable period wherein the yield is considerably below the optimum. Furthermore, in the execution of conversion processes in the presence of stationary beds of solid catalytic materials the decline in catalytic activity of the catalyst takes place at differing rates throughout the catalyst bed during the course of the operation. Therefore, when the effectiveness of the catalyst bed as a whole has declined to the extent where desired yields of product are no longer attained, the catalyst bed is composed of catalytic material varying in' degree of catalytic activity from a state of substantially complete exhaustion to one of but slight impairment. subjecting the catalyst bed as a whole to a treatment directed to the restoration of the catalyst activity'is not only costly, but detrimental to the useful catalyst life of thatpart of the catalyst bed not in need of such drastic treatment. V

The object of the'present invention is to provide an improved process and apparatus for the execution of catalytic conversions with fixed beds of solid catalyst whereby the solid contact material may be employed more advantageously, and the above difiiculties may be substantially overcome. A further object of the invention is to provide an improved process and apparatus especially adapted for the execution of catalytic conversion of hydrocarbons with regenerative contact materials. A still further object of the invention is to provide a process and apparatus especially adapted for effecting catalytic conversions with catalysts containing a volatile or fugitive component. Objects of certain specific aspects of the invention are to provide an improved process and apparatus for the isomerization of hydrocarbons such, in particular, as butane with supported aluminum chloride catalysts whereby the catalyst life is materially increased, the escape of catalyst from the reaction zone is prevented, and a new and more efficient guardtube effect is realized. Further objects and advantages of the process and apparatus of the invention will be apparent from the following detailed description thereof.

According to the process of the invention, the catalyst, after its activity has declined during use to a predetermined level, is not subjected in tototo a treatment to restore the activity, but is divided into portions which are then separately treated under optimum conditions to restore the activity. It has been found that catalytic reactions can be executed in the presence of solid catalytic materials with an efficiency as determined by yield and purity of product, catalyst life, catalyst saving, etc., substantially superior to that of processes disclosed heretofore by intermittently removing less active catalytic material from the catalyst bed as soon as the bed as awhole has fallen below the desireddegree of activity, separately regenerating the less active portion outside of the reaction zone, separately reactivating the remaining part of the bed in situ, and returning the regenerated catalyst to the catalyst bed.

By reactivation as used throughout the specification and claims is meant any treatment at normal or elevated temperature which may be advantageously applied to a partially spent catalyst in situ to restore its catalytic activity. Such reactivation may comprise the passage of suitable fluids through the catalyst bed in situ to remove undesirable material therefrom, deposit a catalytic component therein, or to chemically react with the catalyst or its contaminants. The material removed from the catalyst bed may comprise a spent catalytic component or a deposited material. The material removed may dissolve in the fluid as, for example, where a solvent is passed through the catalyst bed to dissolve deposited reaction products or the fluid may react with the material to be removed as, for example, where chlorine, hydrogen chloride, steam, oxygen, or oxygen-containing gases such as air are passed through the catalyst bed to burn and/or entrain carbon or carbonaceous products therefrom. Materials which may be deposited in the catalyst bed during the reactivation comprise catalytic components. Thus,

finely divided metals or metal compounds may be suspended in a suitable fluidand passed through the catalyst in situ or volatile compounds such, for example, as halogens, metal halides, metal carbonyls, and the like, optionally diluted with inert gases, may be passed through the catalyst in situ.

By the term "regeneration" as used throughout the specification and claims is meant the more drastic treatment accorded a spent or substantially spent catalytic material comprising, for example, one or more of the following: (1) the removal of reaction products which are not amenable to removal by reactivation in situ; (2) the separate recovery of the individual components of the catalyst; (3) the separate restoration of one or more of the components to its original active state; and/or (4) the utilization of the separately recovered catalytic components to restore the active catalytic material.

The process of the invention may be employed in various processes with catalysts of different types. It is advantageous, for example, for the execution of hydrocarbon conversions with regenerative contact masses such as the various synthetic hydrosilicate catalysts and the supported metal oxide-type catalysts. In the treatment of hydrocarbons and hydrocarbon fractions with a catalyst comprising a porous support impregnated with a compound of a metal having hydrogenation-dehydrogenation properties, the process cycle is continued until the production rate has declined to a predetermined level. A portion of the less active catalyst is then removed and subjected to a regeneration treatment exterior to the reaction zone; for example, by treating with acid or by overburning, i. e. treating the catalyst at a somewhat higher temperature with a large excess of air or oxygen to reoxidize and reform the catalytic metal compound. The remaining catalyst is reactivated in.situ; for instance, by conventional buming-oif treatment. The regenerated catalyst is then reintroduced into the reaction zone, preferably at av point adjacent to the most active part of the catalyst bed.

The process of the invention is particularly advantageous for executing conversions with the aid of solid catalysts containing a more or less volatileor fugitive catalytic component. In this case the reactivation in situ may usually be effected by treating the partially spent catalyst with vapors of the volatile component; for example, vapors of a metal carbonyl, metal halide, or the like. Particular catalysts of this type which may be most advantageously used in the present process and apparatus are supported aluminum chloride catalysts, such for example as an adsorptive carrier impregnated with aluminum chloride. These catalysts are useful for many hydrocarbon conversions, and especially for the vapor phase isomerization of saturated hydrocarbons such, in particular, as butane. When effecting reactions with such catalysts according to the process of the present invention, a less active part of the catalyst may be periodically withdrawnand regenerated. The remaining .catalystmay be easily and effectively reactivated'in 'situ by treatment with aluminum chloride vapors.

The reactivation of such catalysts in situ' by the treatment with aluminum chloride vapors is quite unexpected. num chloride catalysts prepared by vapor phase impregnation of an adsorptive carrier with aluminum chloride, though initially substantially saturated with respect to aluminum chloride vapor and though they have lost but a fraction of a per cent of their aluminum'chloride content during the conversion operations, will now; after.use for a period of time in the process, adsorb an additional several per cent of aluminum chloride when treated with aluminum chloride vapors. For instance, a catalyst which was saturated with respect to aluminum chloride at the start of the operation and which lost about one-half per cent of its aluminum chloride content during the conversion operation will.now adsorb an additionl-l amount, for example about 2%-3%, of aluminum chloride when aluminum chloride vapors are passed through it. It has been found that by such a reactivation treatment the catalyst may be brought to a state of activity substantially equal to and often surpassing its original activity. The useful life of the catalyst may thus be considerably prolonged by this method of reactivetion. The effectiveness of this method of catalyst reactivation is illustrated by the following example:

Example I A catalyst prepared by adsorbing aluminum chloride vapors by an adsorptive alumina to sub stantial saturation was used for 650 hours in the isomerization of normal butane, during which i time the conversion to isobutane gradually declined from 65% to 17%; The partially deactivated catalyst was then treated at .a temperature of about 220 C. with vapors of anhydrous aluminum chloride. The thus-treated catalyst was found to have taken up an additional amount of aluminum chloride (about 2%), whereas thereinminum chloride content of the fresh catalyst could not be appreciably increased by further vapor phase impregnation. When the thus-reac-. tivated catalyst was again used in the isomerization of normal butane under comparable conditions, an initial conversion of 60% was attained, and a conversion in excess of 45% was still attained after an additional 150 hours of operation.

Another method of reactivating these catalysts in situ, which may be applied but which is-much less effective than the above-described treat ment with aluminum chloride vapors, is to treat the catalyst for some time with a relatively high concentration of hydrogen chloride, preferably under pressure. I

The less active material intermittently withdrawn from the reaction zone 'is subjected to an appropriate regeneration treatment such "as mentioned above. When effecting reactions with the aid of supported aluminum chloride catalysts such as the above-described isomerization of normal butane, the regeneration may .be effected most advantageously according to the method disclosed in copending application, Serial No. 322,208, filed March 4, 1940, and now issued as Patent 2,254,618 to Frank M. .McMillln, et al. In accordance with this method of regeneration. the withdrawn catalyst is washed It has beenfound that alumiwith aqueous alkali solution, for example a 6 N solution of sodium hydroxide, whereby the aluminum chloride is removed therefrom. The resulting support material substantially free of aluminum chloride is washed with water or an acidic solution to remove excess base and is then activated at an elevated temperature of, fOl' example, about 300 C. This method permits the recovery of the support in a most active and adsorptive condition with a minimum loss due to disintegration, etc. The resulting regenerated support is then impregnated with aluminum chloride vapors to obtain an active isomerizatlon catalyst. y

The following'example illustrates the eife'ctiveness ofthe method of regeneratingthe spent aluminum chloride catalyst: e

Example]! An aluminum chloride catalyst prepared by the vapor phase impregnation of an adsorbent alumina was used for 650 hours for the isomerization of n-butane, during which time its activity gradually decreased, the conversion falling from 66% to 30% in 275 hours, and finally to 17% after 650 hours. A portion of the spent catalyst which was least active and discolored due to contamination by organic material was treated with a solution of 6 N sodium hydroxide for 18 hours. After draining off the alkali, the alumina was washed with water and then activated by heating at about-300 C. Ninety per cent of the adsorptive alumina present in the original catalyst was recovered. The recovered alumina was slightly discolored, but when reimpregnated with aluminum chloride it produced a catalyst fully equal in activity to the original catalyst. When used in the isomerizat'ion of n-bu'tane unprovided with a heating and/or. cooling jacket I4 for the maintenance of the desired tempera ture. 'nections I5 and. l'fi'for' the circulation of any suitable fluid heat carrier therethrough. A plurality of catalyst containers, A, B, C, D, and E,

' are positioned one above the other within the der comparable conditions, it afforded an initial conversion of 65%, and a conversion of 30% after 350 hours of continuous use.

The duration of the conversion step restoring the activity of the catalyst bed may vary considerably within the scope of the invention. The invention, however, makes possible and desirable. the operation at more nearly optimum yields; The intermittent circulation of the catalyst causedby removal of catalyst from one part and return to another part of the catalyst, bed, furthermore, provides improved dis tribution of catalytic material of varying degreesoi catalytic activity in the reaction zone.' thereby avoiding to a- ,substantial degree the difiiculties arising as a result of the tendency oi! the rate of reaction to varythroughout the length of the catalyst bed when operating continuously with a catalyst bed of constant degree of activity throughout.

The process of the invention may be effected in any suitable form of apparatus providing a reaction zone from which the .less active catalyst can be periodically removed and the regenerated catalyst returned thereto. Apparatus particu larly adapted for carrying out reactions in the presence of solid catalytic materials, according to the process of the invention, comprises a converter providing an elongated reaction zone containing a plurality of easily and separately removable catalyst cartridges positioned one above the other within the reaction zone. An apparatus of this type is shown the attached drawing forming a part of this specification and wherein Figure I is an elevational view, partly in section, of a converter providing a reaction chamber containing a plurality of catalyst conbefore reaction chamber. The catalyst containers comprise non-perforated metal sides H, a per-. forated bottom; for example, a supported screen l8, and an open top. The top and bottom of the catalyst container are provided with suitable co-operating members; for example, flush step joints i9 and, permitting the formation of substantially vapor-tight connection between adjoining containers. A screen 22 may, if-desired, be positioned above the catalyst 2| within the container; Each container is preferably provided at its upper part with a supporting means :23; for example, two bars of metal rigidly fixed to theupper part .of the container at right angles to one another, to which a member of a suitable lifting, means may be hooked to enable the container to be withdrawn from and inserted into the reaction chamber. The length of each 'catalyst container may vary depending upon the nature of the particular conversion operation and the type of catalyst used. Also, though the drawing shows the use of five catalyst con- I tainers, it is to be understood that the invention is not limited to this number of containers, and

a greater or lesser number may be used. The cross-sectional area oi the catalyst containers is preferably such that intimate contact will be maintained between substantially the entire outer wallof thecontainer' I! and the inner wall of the reaction chamber I3, thereby-assurcontainers.

ing a suitable heat transfer between the catalyst and the heat-controlling medium in jacket N.

I The lower part of the reaction chamber is provided with supporting means, for the catalyst The supporting means will preferably consist of a means; for example, a flush' step joint 24, co-operating with joint IQ of the catalyst container in position E to form a substantially vapor-tight connection therewith. The catalyst containers will divide reaction chamber l3 into a plurality of inter-communicating compartments through which the reactants are caused to flow. The converter is pro.- vided with an easily removable head, such as a hinged cover 29, to permit easy access to the reaction zone for the introduction and removal of the catalyst containers.

plurality of compartments, with facility of catalyst temperature control through the wall of the container and without danger of bypassing reactants about any of the compartments. The ease of handling of the individual containers'facilitates the intermittent withdrawal of less active catalyst from the bed and enables the efficient treatment ofseparate portions of the catalyst bed.

Jacket I4 is provided. with suitable con- It furthermore enables the efficient distribution and intermittent redistribution of the separate catalyst portions throughout the reaction zone. The described converter is particularly advantageous for the execution of reactions at elevated ecution of a variety of catalytic reactions. However, for the purpose of a more ready understanding thereof, its use will be described with reference to its application in the catalytic isomerization of butane. Butane, which has been preferably preheated to a temperature of, for example, from about 90 C. to about 150 C., is forced at a pressure of, for example, from about 150 to about 250 pounds per square inch by means not shown in the drawing, through line i0, controlled by valve ll, into the lower part of converter l2. All or a part 'of the catalyst containers are filled with a suitable isomerization catalyst such, for instance, as an adsorptive alumina impregnated with aluminum chloride tosubstantial saturation by treatment with aluminum chloride vapors. Hydrogen chloride, preferably in the amount of from about 1% to about 25% of the charge, is introduced into line through line 25, controlled by valve 26. A temperature control fluid; for example, water, oil, steam, or the like, is circulated through jacket l4 to maintain the desired temperature of, for example, from 90 C. to about 150 0., within the reaction zone. The reaction product containing isobutane leaves the reactor via line 21 and valve 28.

When the effectiveness of the catalyst bed as a whole has declined to the extent where desired yields are no longer obtained, the operation is interrupted. The catalytic activity of the catalyst in containers A to E, inclusive, will be found to decrease progressively in that order.

The catalyst in containers which held positions A to D, inclusive, in the completed conversion operation are intermittently reactivated by treatment with aluminum chloride vapors. This phase of the operation is preferably effected in situ. All containers are, therefore, removed from the reaction chamber and containers which held positions A to D, inclusive, are reinserted into the reaction zone in the same relative position to one another; the container which held position D in the completed phase of the operation now occupying the lowest position, E. -Anhydrous aluminum chloride vapors are introduced into the lower part of the reaction zone through line 30, con,- trolled by valve 3|, and passed upwardly through the containers, the contents of which will again attain their desired degree of activity. By closing valve 28 and opening valve 32 during the impregnation operation, excess aluminum chloride vapors are eliminated from the system through line 33. To prevent condensation of aluminum chloride vapors in the reaction zone, the reaction chamber is maintained at a temperature of, for example, from about 185 C. to about 300 C. during this reactivation operation. Lines 30 and 33 are preferably insulated.

Although the catalyst activity may be restored by reactivation in situ, the duration of the activity is somewhat shorter after each-reactivation and the number of reactivations by this method is therefore limited by the attainment ofa duration of activity below the desired length or by the complete exhaustion of the catalyst.

In the process of the invention, the container in the bottom position is intermittently removed. Each of the remaining containers assumes the next lower position and the catalyst is reactivated above, to recover and regenerate the components of the catalyst. The regenerated catalyst is returned to the reaction chamber in position A above the remainder of the bed which has been reactivated in situ, and the conversion phase 01 the cycle is begun. The regenerated support may be placed in position A in the reaction Zone and be impregnated with aluminum chloride therein simultaneously with the reimpregnation of the remainder of the catalyst bed. The passage of the aluminum chloride vapors through the containers in this case is continued until the topmost container containing the regenerated support has become substantially saturated with respect to aluminum chloride.

When utilizing as catalyst a material having an appreciable degree of solubility in the reactants or which has a relatively high vapor pressure, as, for example, aluminum chloride, some of the catalyst will tend to pass out of the reaction zone, together with the reaction products, thereby causing serious trouble due to clogging of parts of apparatus, contamination of product, etc. By filling the container in position A with a suitable adsorbent; for example, the adsorbent alumina used as support for the aluminum chloride catalyst, it is possible to substantially completely avoid the loss of catalyst from the reaction zone. In a preferred method of carrying out the isomerization of butane in accordance with the invention, the regenerated catalyst support is therefore inserted in position A after the rest of the catalyst bed has been reactivated by treatment with aluminum chloride vapors.

The amount of aluminum chloride upon an adsorbent carrier must exceed a well defined minimum to attain desirable effectiveness as an isomerization catalyst; for example, above about 8% for the activated alumina carrier used in the present illustrative example. Therefore, the regenerated support material may be placed in the reaction zone prior to the passage of the aluminum chloride vapors therethrough and the duration of the passage of the vapors controlled to allow the aluminum chloride content of container in position B to exceed this minimum, and the contents of container in position A to remain well below this minimum. In this way, container A, although containing some aluminum chloride,

will still function to prevent the escape of catalyst from the reaction zone. After completing a conversion phase of the cyle in position A, the container will'move to position B and be saturated with aluminum chloride prior to the next conversion step.

The following example is given to illustrate the effectiveness of the use of the adsorbent alumina in position A in preventing the escape of catalyst from the reaction zone.

asi es? Example iii the liters of aluminum chloride catalyst pre pared by the vapor phase impregnation of an' adsorbent alumina were placed in cartridges in a. suitable cylindrical reactor. A l-liter cartridge of activated alumina was placed in the reactor above the catalyst cartridges. The reactor was closed and heated to a temperature in the range of from 160 C. to 135 C. and maintained in this tennperature range while normal butane vapors con-- taining from 3 mol per cent to 20 mol per cent H61 were passed therethrough under a pressure in the range of from 1'75 to 250 pounds. pounds of feed were passed through the reactor at the above conditions in a period of 2,281 hours of operation. At the termination of this operation, it was found that the loss in weight of the catalyst was almost equal to the gain in weight or the activated alumina, less than. 0.7% of catalyst having been lost from the reactor.

it is seen that during the course of the successive operating cycles the catalyst moves downward in the reaction zone as its catalytic efieca tiveness declines, the exhausted catalyst being intermittently removed from the lowest part of the catalyst bed to be regenerated and again form the upper part of the bed. In one preferred modification of the invention particularly adapted tor-the vapor phase isomerization of hydrocarbons, the lower section of the catalyst is used as a pretreating zone. To this object, container in position E is filled with an adsorptive material which serves to remove entrained matter from the reactants and otherwise pretreat the reactants prior to their contacting the catalyst, thereby considerably prolonging the life of the catalyst and the length of each individual conversion step of the cycle. It has been found that the adsorbent material which has been in position A for a conversion period and which contains adsorbed aluminum chloride removed from the reaction products constitutes an ideal material for this purpose, Its particular advantage resides in the tact that it has been. admirably conditioned for this purpose during the previous conversion step. lit has given off all themoisture which a fresh batch of similar adsorbent would liberate at the operating conditions as a result of its displacement by the hydrogen chloride in the charge, and which moisture is detrimental to the life of the aluminum chloride catalyst. It, furthermore, is saturated with hydrogen chloride, thereby avoiding the difficulties occasioned at the start of each conversion step with fresh adsorbent in the pretreater due to the removal of hydrogen chloride from the charge by the pretreating material. In this modification of the process of the invention, therefore; container in position A is shifted to position E at the end of each conversion 7 step. In this method of operation, only the containers in positions B, C, and D are filled with. catalytically effective material. At the termination of the conversion step, contents of con talner D, which now contains the least active catalyst, are subjected to the above-described treatment to recover and regenerate the adsorbent support whereupon it is moved to position A. The contents of containers E, B, and C are sub-- jected at the end of the conversion stepto a reactivation treatment such as described above and will form the catalytic section of the catalyst bed in the subsequent conversion step. During :ontinued operation comprising the successive cycles, each including a conversion step and a step of restoring the catalyst to the desired catalytic activity, the material comprising the catalyst bed. will constantly move through the reaction zone along the following course: Beginhing as adsorbent in position A, it will move to position E. Upon completion of its function'as pretreater, it will move to position B and be impregnated with aluminum chloride. will'move downwardly through the catalytic section of the reaction zone as its catalytic effectiveness decreases until it attains positionD. After completinge conversion step in position D, it is treated to recover and regenerate the support material and is moved to position A to repeat the intermittent how.

Although the invention has been described in its ap lication to a process utilizing an upward flow through the converter, it is to be understood that the invention is not limited thereto and the reactants may, if desired, be passed downwardly through the converter.

The constant circulation of the catalyst in the isomerization process of the invention enabling the contacting of the reactants with catalyst of gradually increasing activity permits the attaln-. ment of uniform reaction rates throughout the reaction zone. This, in addition to the novel method of reactivating the aluminum chloride catalyst by treatment with aluminum chloride vapors and the ease of catalyst handling, permits the use of longer conversion periods of optimum conversion conditions. The constant circulation of the catalyst, furthermore, avoids difficulties such as fouling of the. catalyst and clogging of the catalyst bed toward the outlet end of the reaction zone in operations wherein the product has a greater tendency to undergo side reactions than the charge material. These, in addition to the many advantages inherent in intermittent withdrawal of the least active part of the catalyst bed, its separate regeneration outside the catalyst zone, and the reactivation oi the remainder of the bed in situ, provide a process, the efiiciency and economical advantages of which considerably exceed those of processes available heretofore for the execution of catalytic reactions in elongated beds of solid catalyst.

The invention has been described in detail with reference to the isomerization of butane in the presence of a supported aluminum chloride catalyst. It is to be understood, however, that the invention is in no wise limited in its ap licability to this particular conversion operation and may be applied with advantage to the execution of many catalytic conversions efiected in the presence of many types of catalytic materials. Catalytic conversions typical of the many which can be effected with improved eiiiciency with the aid of the process and apparatus of the invention comprise the isomerizatioh of saturated hydrocarbons in the presence of catalysts comprising a halide of aluminum, molybdenum sulfide, or the like; hydrogenation of organic compounds in the presence of catalysts comprising supported hydrogenating metal catalysts; dehydrogenation of hydrocarbons in the presence of metal oxide dehydrogenation catalysts; alkylation and/or polymerization of hydrocarbons in the presence of solid phosphoric acid catalysts; aromatization of hydrocarbons in the presence of catalysts comprising oxides and/or sulfides of heavy metals such as aluminum, chromium, molybdenum,

molybdic and tungstic acid; the isomerization of olefines with catalysts comprising base-exchange catal sts and/or acid adsorbents; catalytic arach- Thence, it

ing of hydrocarbons in the presence of synthetic hydrosilicate catalysts; oxidation of saturated and/ or unsaturated hydrocarbons with silver catalvsts; desulturization of hydrocarbon fractions in the presence of catalysts comprising, metals such as iron, copper, etc.; and the like.

This is a division of my co-pending application, Serial No. 376,194, filed January 27, 1941.

I claim as my invention:

1. A converter for effecting catalytic conversions of fluid reactants which comprises an elongated reaction chamber, means for maintaining a temperature controlling medium in direct contact with the external walls of said reaction chamber, a plurality of catalyst containers havme open tops and perforated bottoms removably positioned one above the other within said reaction chamber, said containers being provided with co-operating members forming substantially vapor-tight connections between adjoining containers, the sides of said containers being in contact substantially throughout their entire length with the Wall of said reaction chamber, fluid inlet at one end or said reaction chamber, and fluid outlet at the other end or said reaction chamber.

2. A converter for effecting catalytic conversions of fluid reactants which comprises an elongated reaction chamber, means for maintainin: a temperature controlling medium in direct contact with the external walls of said reaction chamber, a plurality of catalyst containers having open tops and perforated bottoms removably positioned one above the other within said reaction chamber, the sides of said containers being in contact substantially -throughout their entire length with the wall or said reaction chamber, fluid inlet at one end or said reaction chamber, and fluid outlet at the other end of said reaction chamber. k

3. A converter for efiecting catalytic conversions of fluid reactants which comprises an elongated reaction chamber, a plurality of catalyst containers having open tops and perforated bottoms removably positioned one above the other within said reaction chamber, said container: being provided with co-operating members torming substantially vapor-tight connections between adjoining containers, fluid inlet connections at one end of said reaction chamber, and fluid outlet connections at the other end of said reaction chamber.

- FRANK M. McMILLAN. 

